package com.imooc.o2o.util;

import java.security.Key;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;

import org.apache.commons.codec.binary.Base64;

public class DESUtil {
	private static Key key;
	private static String KEY_STR = "myKey";
	private static String CHARSETNAME = "UTF-8";
	private static String ALGORITHM = "DES";
	
	static {
		try {
			// 生成DES算法对象
			KeyGenerator generator = KeyGenerator.getInstance(ALGORITHM);
			// 运用SHA1安全策略
			SecureRandom secureRandom = SecureRandom.getInstance("SHA1PRNG");
			// 设置上密钥种子
			secureRandom.setSeed(KEY_STR.getBytes());
			// 初始化基于SHA1的算法对象
			generator.init(secureRandom);
			// 生成密钥对象
			key = generator.generateKey();
			generator = null;
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
	}
	
	/**
	 * 获取加密后的信息
	 * @param str
	 * @return
	 */
	public static String getEncryptString(String str) {
		try {
			byte[] bytes = str.getBytes(CHARSETNAME);
			Cipher cipher = Cipher.getInstance(ALGORITHM);
			cipher.init(Cipher.ENCRYPT_MODE, key);
			byte[] doFinal = cipher.doFinal(bytes);
			return Base64.encodeBase64String(doFinal);
		} catch (Exception e) {
			throw new RuntimeException(e);
		}	
	}
	
	/**
	 * 获取解密后的信息
	 * @param str
	 * @return
	 */
	public static String getDecryptString(String str) {
		try {
			byte[] bytes = Base64.decodeBase64(str);
			Cipher cipher = Cipher.getInstance(ALGORITHM);
			cipher.init(Cipher.DECRYPT_MODE, key);
			byte[] doFinal = cipher.doFinal(bytes);
			return new String(doFinal, CHARSETNAME);
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
	}
	
	public static void main(String[] args) {
		System.out.println(getEncryptString("123456"));
		System.out.println(getDecryptString("WnplV/ietfQ="));
	}
}
